The plasminogen activator inhibitor 1 (PAI-1), encoded by the SERPINE1 gene, serves as a key inhibitor of the tissue plasminogen activator (tPA) in the extracellular space, and has been associated with an increased risk of depression and the response of selective serotonin reuptake inhibitors [23,24]. The gene discussed is SERPINE1; the disease is major depressive disorder.